Delivery point validation system

ABSTRACT

Systems and methods consistent with the present invention encode a list so users of the list may make inquires to the coded list without the entire content of the list being revealed to the users. Each item in the list turns on one or more bits in the array  110 . Once each item in the list has been encoded by an encoder, a bit array with high and low values is used to represent the items in the list. The bit array may be embodied in a validation system for allowing users to query the list to determine whether an inquiry item is on the list  105 . The validation system determines which bits to check by executing the same coding process executed by the encoder. If all the bits are high, then the inquiry item is determined to be part of the list, if at least one of the bits is low, then the inquiry item is determined not to be part of the original list. An exemplary encoder and validation system comprises a standardizer, a hashing function unit, an extraction circuit, and an offset circuit.

DESCRIPTION OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a system and method forvalidating or confirming information.

[0003] 2. Background of the Invention

[0004] Many occasions arise when validation or confirmation ofinformation is desired before taking a particular action. For example, aperson may want to confirm that an address is a valid address beforesending a valuable item or sensitive information to the address. Asanother example, a delivery business may want to confirm an addressbefore sending a product. There are also occasions when validating anaddress can be lifesaving. For example, fire departments, ambulancecompanies, and police departments may want to confirm an address toefficiently respond to an emergency. There are times when other types ofinformation, besides addresses, need to be validated or confirmed. Forexample, a traffic officer may need to confirm that a driver's licenseis valid before permitting a person to drive.

[0005] Despite the need to validate or confirm information, in today'sinformation technology age, businesses and individuals are concernedabout privacy and information security. Furthermore, businesses considerinformation to be a valuable company asset. Because of the concernsabout information security and the view that information is an asset,owners of information may want to keep their information private andsecure. On the other hand, an owner of information may also want toexploit the information by providing the information to others. Forexample, an owner of information comprising a list of all persons withaccess to a building may want to provide the list to a security companyso that the security company may confirm whether a person seekingentrance into the building is on the list. However, for privacy reasons,the owner may not want to reveal to the security company all persons onthe list. That is, the owner may feel that the list should only berevealed one person at a time as a person seeks entrance to thebuilding. If a person on the list never seeks entrance to the building,then the security company never needs to know that the person is on thelist. Based on the above concerns, it would be advantageous if an ownerof information could provide the information to others for inquirypurposes, the information being in an encrypted format so thatinformation may remain confidential.

SUMMARY OF THE INVENTION

[0006] In accordance with the invention, there is provided a method forrepresenting a list of items using a bit array wherein each bit in thebit array is initialized to a first value. The method comprisesconverting each item into a N-bit object and determining bit positionsbased on the N-bit object. The method further comprises setting bits ofthe bit array to a second value at the determined bit positions.

[0007] There is further provided a method for determining whether aninquiry item is on a list of items. The list of items is represented bya bit array having first and second values. The method comprisesconverting the inquiry item into a N-bit object in a same manner that anitem on a list of items is converted to produce a bit array representingthe list of items. The method further comprises determining bitpositions based on the N-bit object in a same manner that bit positionsare determined for producing the bit array. Still further, the methodcomprises determining that the inquiry item is on the list if the bitsof the bit array equal a second value at the determined bit positionsand determining that the inquiry item is not on the list if at least onebit of the bit array does not equal a second value at the predeterminedbit positions.

[0008] Additional objects and advantages of the invention will be setforth in part in the description which follows, and in part will beobvious from the description, or may be learned by practice of theinvention. The objects and advantages of the invention will be realizedand attained by means of the elements and combinations particularlypointed out in the appended claims.

[0009] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate one embodiment ofthe invention and together with the description, serve to explain theprinciples of the invention.

[0011]FIG. 1 illustrates a process of converting a list of items into abit array consistent with an embodiment of the present invention.

[0012]FIG. 2 illustrates a process of determining whether an inquiryitem is on a list represented by a bit array consistent with anembodiment of the present invention.

[0013]FIG. 3 illustrates an encoder for encoding a list of items into abit array consistent with an embodiment of the present invention.

[0014]FIG. 4 illustrates an exemplary method of extracting bit samplesconsistent with an embodiment of the present invention.

[0015]FIG. 5 illustrates a validation system for determining whether aninquiry item is on a list consistent with an embodiment of the presentinvention.

[0016]FIG. 6 illustrates an exemplary method of standardizing an addressconsistent with an embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

[0017] Reference will now be made in detail to the present embodiment ofthe invention, an example of which is illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

[0018] Systems and methods consistent with the present invention encodea list so that users of the list may make inquires to the coded listwithout the entire content of the list being revealed to the users. FIG.1 illustrates an example of a coded list 110 that may be derived from alist 105 based on an encoder 107 in accordance with the presentinvention. The list 105 may comprise addresses, names, license numbers,or any other type of information. In this example, the coded list 110 isan array of bits (i.e., 1, 2, 3, etc.) The size of the bit array 110 maybe chosen to reduce the number of false positives that may result when auser makes an inquiry to the list 105, as discussed in greater detailbelow.

[0019] Each item 102 in the list 105 turns on one or more bits in thebit array 110. That is, initially all the bits in the bit array 110 arelow and are changed to high based on an item 102 in the list 105. Morespecifically, each item 102 in the list 105, once encoded by encoder107, indicates which bit or bits to turn on in the bit array 110 torepresent the item 102. For example, the first item 102 in the list 105may turn on bits 1, 3, 11, as shown in FIG. 1. The second item 102 inthe list 105 may turn on bits 5, 7, and 10, and so on. Multiple items102 in the list 105 may turn on the same bit. For example, a first,fourth, and tenth item 102 in the list 105 may turn on bit 11.Practically speaking, once a bit is turned on by an item 102, it remainson and is unaffected if other items 102 indicate that it should beturned on.

[0020] Each item 102 may turn on one or multiple bits in the bit array110. In the example above, each item 102 turns on three (3) bits.However, a greater or lesser number of bits may be turned on for eachitem 102. The number of bits to turn on may be chosen to reduce thenumber of false positives that may result when a user makes an inquiryto the list 105, as discussed in greater detail below.

[0021] Once the encoder 107 has encoded each item 102 in the list 105, abit array 110 with high and low values is used to represent the items102 in the list 105. The bit array 110 may then be used by third partiesfor inquiry purposes without the content of the list 105 being revealed.Referring to FIG. 2, the bit array 110 may be embodied in a validationsystem 207 for allowing users to query the list 105 to determine whetheran inquiry item 202 is on the list 105. For example, assume that the bitarray 110 represents a list of all person with access to a building.Users of the bit array 110 may query the list 105 to determine whether aname is on the list 105 by inputting the name, i.e., the inquiry item202, into the validation system 207. The validation system 207 mayreturn a “yes” response, indicating that the name is on the list, or mayreturn a “no” response, indicating the name is not on the list.

[0022] The inquiry item 202 undergoes the same encoding process that anoriginal list item 102 undergoes. That is, the validation system 207executes the same encoding process executed by the encoder 107. Recallthat for the original list items 102, the encoder 107 determines whichbits of the bit array 110 to turn on. For an inquiry item 202, thevalidation system 207 determines which bits of the bit array 110 tocheck. If all the bits checked are high, then the inquiry item 202 isdetermined to be part of the list. If at least one of the bits checkedis low, then the inquiry item 202 is determined not to be part of theoriginal list 105. For example, assume that that the validation system207 processes the inquiry item 202, determining which bits to check. InFIG. 2A, the validation system 207 checks bits 1, 5, and 7. Because bits1, 5, and 7 are all high, the validation system 207 determines that theinquiry item 202 is on the original list 105 and returns an affirmative.As another example, in FIG. 2B, the validation system 207 checks bits 2,3, and 11. Because bit 2 is low, the validation system 207 determinesthat the inquiry item 202 is not on the original list 105 and returns anegative response. In this way, an owner of a list may provide a codedlist to third parties to determine whether an item is on a list, withoutrevealing the content of the list.

[0023]FIG. 7 illustrates an exemplary system network 700 in which topractice the present invention. The network 700 consists of a server710, a workstation 720, and a communication link 730. The server 710 maystore the bit array 110 and validation system 207 used to determinewhether an inquiry item 202 is on a list 105. The workstation 720 may bea personal computer having a keyboard for inputting an inquiry item 202.The communication link 730 transmits the inquiry item 202 to the server710 wherein the validation system 207 processes the inquiry item 202 andreturns an affirmative or negative response via the communication link730 to the workstation 720. The network 700 may be a local area network(LAN) or a wide area network (WAN) to include the Internet, for example.The network 700 may be wireless. In an alternate embodiment, astand-alone workstation may store the bit array 110 and validationsystem 207 and a user may input an inquiry item 202 via theworkstation's keyboard or other input device to determine locallywhether the inquiry item 202 is on a list 105.

[0024]FIG. 3 illustrates an exemplary encoder 107 for encoding a list105, resulting in an array of bits 110, as described above. The encoder107 comprises a standardizer 310, a hashing function unit 320, anextraction circuit 330, and an offset circuit 340.

[0025] The standardizer 310 converts an input into a standard formatprior to encoding. This step may be desirable for a list that maycontain multiple variations of the same information. For example, a listthat contains addresses may have multiple entries of the same address indifferent formats. It may be more efficient to encode a singlerepresentation of the same item than to encode each variation of theitem. For instance, assume that multiple variations for an address areprovided on a list. The entries include: 123 Main Street, Apartment 456;123 Main St., Apt. 456; and 123 Main St., # 456. The standardizer 310may convert each of these entries to 123 Main St. 456 and encode thisrepresentation of the address rather than encoding each variation of theaddress.

[0026] The standardizer 310 may standardize a list in accordance withthe teachings disclosed in the provisional application entitled, “AMethod For Standardizing A Mailing Address, Enhanced Modified DeliveryPoint”, by Robert Snapp, filed on Mar. 22, 2001, which is incorporatedby reference. The provisional application discloses a method forstandardizing a mailing address into a numeric string. As shown in FIG.6, a mailing address may be standardized by concatenating the nine-digitzip code of the address; a seven digit segment comprising the addressnumber (i.e., the primary number) preceding the address name and theaddress number (i.e., the secondary number) following the address name(e.g., the suite or apartment number); and a three digit segmentcomprising a numeric representation of up to two alphanumeric characterswhich may appear in the primary or secondary number (e.g., Apt. K). Theseven-digit segment may be padded with leading zeros if the total numberof digits in the primary number and secondary number is less than sevendigits. For the three digit segment, the numeric representation of asingle alphanumeric character in the primary or secondary number may beas follows: space=0, A=1, B−2, . . . , Z=26. The numeric representationof two alphanumeric characters in the primary or secondary number may bedetermined by multiplying the numeric value of the first alphanumericcharacter by 27 and then adding the value of the second alphanumericcharacter (e.g., AA=1×27+1; ZZ=26×27+26). It will be understood by thoseof ordinary skill in the art that a different standardization techniquemay be used to standardize a list of items.

[0027] Once a list item 102 is standardized, it is input to the hashingfunction unit 320. The hashing function unit 320 may execute a one-wayhash function, i.e., a function that transforms an input item making itdifficult to impossible to reproduce the input. For example, a one-wayhash function may take an input and produce an N-bit object having noobvious relationship to the input. Furthermore, a hash function mayproduce significantly different outputs for similar, but not identical,inputs. In an exemplary embodiment, the hashing function unit 320executes a secure hashing algorithm, SHA-1, which was developed by theNational Institute of Standards and Technology (NIST) and is an ANSIstandard encryption technique.

[0028] The SHA-1 transforms an input into a 160-bit (20 byte) objectcalled a message digest. The SHA-1 sequentially processes blocks of 512bits when computing the message digest. Therefore, the SHA-1 pads aninput bit string to produce a bit string with a length that is amultiple, n, of 512 prior to processing the input bit string. The SHA-1pads the input bit string by appending a “1” to the input bit string,followed by a number of “0”s depending on the original length of theinput bit string, followed by a 64-bit integer representing the originallength of the input bit string. The number of “0”s appended to the inputbit string equals a number which will produce a bit string with a lengththat is a multiple of 512 once the “1”, the “0”s, and the 64-bit integeris added to the input bit string. For example, to pad an input bitstring with a length of 40, a “1” is appended to the input bit string,followed by 407 “0”s, followed by a 64-bit integer representing thelength of the input bit string (i.e., 40).

[0029] The padded input bit string is viewed as a sequence of n blocksM₁, M₂, . . . , M_(n), where M_(i) contains 16 words. Constant words K₀,K₁, . . . , K₇₉ are used in the SHA-1, where, in hex:

K _(t)=5A827999 (0≦t≦19)

K_(t)=6ED9EBA1 ((20≦t≦39)

K_(t)=8F1BBCDC (40≦t≦59)

K_(t) =CA52C1D6 (60≦t≦79)

[0030] To generate the 160-bit message digest, the SHA-1 processes theblocks, M_(i), for i=1, . . . , n. For each block, M_(j), the SHA-1computes constants words H₀, H₁, H₂, H₃, and H₄. Initially, for blockM₁, H₀=67452301, H₁=EFCDAB89, H₂=98BADCFE, H₃=10325476, and H₄=C3D2E1F0(all in hex). H_(j) for j=0, 1, 2, 3, 4 for subsequent blocks, M_(j),initially equals the H_(j) computed for the previous block. The H₀, H₁,H₂, H₃, and H₄ computed for block M_(n) is the 160-bit message digest.

[0031] Each block, M_(i), is processed in the following manner. First,block M_(i) is divided into 16 words, W₀, W₁, . . . , W₁₅. In addition,the following variables are initialized: A=H₀, B=H₁, C=H₂, D=H₃, andE=H₄. For t=0 to 79, the SHA-1 computes the following equations:

TEMP=S ⁵(A)+f _(t)(B,C,D)+E+W _(t) +K _(t)

E=D; D=C; C=S ³⁰(B); B=A; A=TEMP

[0032] where:

[0033] S^(n)(X) is a circular shift of X by n positions to the left

f _(t)(B,C,D)=(B{circumflex over ( )}C)V(˜B{circumflex over ( )}D)(0≦t≦19)

f _(t)(B,C,D)=BXORCXORD (20≦t≦39)

f _(t)(B,C,D)=(B{circumflex over ( )}C)V(B{circumflex over( )}D)V(C{circumflex over ( )}D) (40≦t≦59)

f _(t)(B,C,D)=BXORCXORD (60≦t≦79)

W _(t) =S ¹(W _(t-3) XORW _(t-8) XORW _(t-14) XORW _(t-16)) (16≦t≦79)

[0034] X{circumflex over ( )}Y =bitwise logical “and” of X and Y

[0035] X v Y =bitwise logical “inclusive-or” of X and Y

[0036] X XOR Y =bitwise logical “exclusive-or” of X and Y

[0037] ˜X =bitwise logical “complement” of X

[0038] X+Y =(x+y) mod 2 ³² converted to a word, where x is the integerof X and y is the integer of Y.

[0039] After the above equations have been computed, H_(j) is computedas follows:

H ₀ =H ₀ +A

H ₁ =H ₁ +B

H ₂ =H ₂ +C

H ₃ =H ₃ +D

H ₄ =H ₄ +E

[0040] As stated above, the H₀, H₁, H₂, H₃, and H₄ computed for blockM_(n) is the 160-bit message digest.

[0041] The extraction circuit 330 extracts multiple n-bit samples fromthe N-bit object input from the hashing function unit 320. If the sizeof the bit array 110 is equal to 2^(×)bits, then the size of each sampleextracted from the N-bit object should be equal to or greater than xbits. The number of samples to extract from the N-bit sample maycorrespond to the number of bits that are turned on during the encodingprocess for each list item 102. In the case of the SHA-1, for example,the extraction circuit 330 may extract nine (9) 32-bit samples from the160-bit object input from the hashing function unit 320. FIG. 4illustrates an example of how an extraction circuit 330 may extractmultiple 32-bit samples 1 through 9 from a 160-bit object 410. Eachnumber block (i.e., 0, 1, 2, etc.) represents a byte. The multiple n-bitsamples extracted by the extraction circuit 330 are input to the offsetcircuit 340. It will be understood by a person of ordinary skill in theart that a different extraction technique may be employed.

[0042] The offset circuit 340 determines which bits in the bit array 110to turn on based on the n-bit samples from the extraction circuit 330.Each n-bit sample turns on a bit in the bit array 110. Therefore, inFIG. 4, a total of 9 bits in the bit array 110 will be turned based onthe bit samples 1 through 9, respectively. FIG. 4 illustrates how a32-bit sample for the 160-bit object 410 may be used to determine whichbit in a bit array 110 to turn on. As shown in FIG. 4, a 32-bit sampleis divided into 2 objects. The first object comprises the leftmost threebits in the 32-bit sample. The second object comprises the remaining 29bits in the 32-bit sample. The second object determines which byte inthe bit array 110 contains the bit to be turned on. The first objectdetermines which bit in the byte to turn on. For example, a secondobject may determine that the first byte of a bit array 110 contains thebit to be turned on. The first object may determine that the third bitof the first byte of the bit array 110 is to be turned on, asillustrated in FIG. 1. It will be understood by a person of ordinaryskill in the art that a different technique may be employed to determinewhich bits to turn on in the bit array 110.

[0043] The encoder 107 may be implemented in software, firmware,hardware, or any combination thereof. The bit array 110 may be stored inany semi-permanent or permanent holding place for digital data, such asa magnetic disk (e.g., floppy disk or hard disk), optical disk (e.g.,CD, CD-ROM, DVD-ROM), or magnetic tape.

[0044] As discussed above, the size of the bit array 110 or the numberof bits the encoder 107 turns on may be chosen to reduce the number offalse positives that may result when a user makes an inquiry to the list105. False positives result when the validation system 207 returns anaffirmative response although an inquiry item 202 is not on the list105. This occurs because all the bits checked by the validation system207 for the inquiry item 202 coincidentally where turned on by one ormore other list items 102 during the encoding process. The probabilityof a false positive equals $\left( \frac{S}{M} \right)^{k},$

[0045] where M equals the number of bits in the bit array 110, S equalsthe total number of bits turned on in the bit array 110, and k equalsthe number of bits the encoder 107 turns on per list item 102.Furthermore, S, the total number of bits turned on in the bit array 110,is approximately equal to ${M\left( {1 - ^{\frac{Nk}{M}}} \right)},$

[0046] where N equals the number of list items 102. M, the number ofbits in the bit array 110, and k, the number of bits turned on per listitem 102, may be chosen to minimize the number of false positives basedon the above equations. However, a higher false positive rate above theminimum may be chosen based on other considerations such as processingspeed.

[0047]FIG. 5 illustrates an exemplary validation system 207 forvalidating an inquiry item 202. As discussed above, the validationsystem 207 utilizes the same encoding process as used by the encoder107. Therefore, the validation system 207 of FIG. 5 is similar to theencoder 107 of FIG. 3. The validation system 207 comprises astandardizer 510, a hashing function unit 520, an extraction circuit530, and an offset circuit 540.

[0048] When an inquiry is made to determine whether an inquiry item 202is on a list, it may be desirable to standardize the inquiry item 202prior to determining whether the inquiry item 202 is on the list. If aninquiry item 202 is not standardized, the validation system 207 mayincorrectly determine that the inquiry item 202 is not on the listsimply because it is in a different format. The standardizer 510 mayeliminate this problem by converting the inquiry item 202 into astandard format prior to validating. The standardizer 510 may operate ina same manner as the standardizer 310. Once an inquiry item 202 isstandardized, it is input to the hashing function unit 520.

[0049] The hashing function unit 520 executes the same one-way hashfunction that is executed by the hashing function unit 320, generatingan N-bit object. The N-bit object is input to the extraction circuit530.

[0050] The extraction circuit 530 extracts multiple n-bit samples fromthe N-bit object in the same manner that the extraction circuit 330extracts multiple n-bit samples. The multiple n-bit samples extracted bythe extraction circuit 530 are input to the offset circuit 540.

[0051] The offset circuit 540 determines which bits in the bit array 110to test based on the n-bit samples from the extraction circuit 530. Theoffset circuit 540 makes this determination in the same manner that theoffset circuit 340 determines which bits in the bit array 110 to turnon. The validation system 207 tests the bits indicated by the offsetcircuit 540. As discussed above, if the bits tested are all high, thenthe validation system 207 determines that the inquiry item 202 is on thelist 105; if at least one of the bits is low, then the validation system207 determines that the inquiry item 102 is not on the list 105.

[0052] The validation system 207 may be implemented in software embodiedlocally in a workstation or in a server as shown in FIG. 2.Alternatively, the validation system 207 may be implemented in firmware,hardware, or any combination of software, firmware, and hardware.

[0053] Other embodiments of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. It is intended that the specificationand examples be considered as exemplary only, with a true scope andspirit of the invention being indicated by the following claims.

What is claimed is:
 1. A method for representing a list of items using a bit array wherein each bit in the bit array is initialized to a first value, comprising: converting each item to a N-bit object; determining bit positions based on the N-bit object; and setting bits of the bit array to a second value at the determined bit positions.
 2. The method according to claim 1, further comprising: standardizing each item of the list.
 3. The method according to claim 2, wherein the list comprises addresses having a nine-digit zip code, a primary address number, and a secondary address number and standardizing comprises concatenating the nine-digit zip code, the primary address number, and the secondary address number.
 4. The method according to claim 1, wherein converting comprises computing a hash function for each item.
 5. The method according to claim 4, wherein the hash function is the secure hashing algorithm, SHA-1.
 6. The method according to claim 1, wherein determining comprises: extracting multiple n-bit samples from the N-bit object; and determining, for each n-bit sample, a bit position based on the n-bit sample.
 7. A method for determining whether an inquiry item is on a list of items, wherein the list of items is represented by a bit array having first and second values, the method comprising: converting the inquiry item into a N-bit object in a same manner that an item on a list of items is converted to produce a bit array representing the list of items; determining bit positions based on the N-bit object in a same manner that bit positions are determined for producing the bit array; and determining that the inquiry item is on the list if the bits of the bit array equal a second value at the determined bit positions and determining that the inquiry item is not on the list if at least one bit of the bit array does not equal a second value at the predetermined bit positions.
 8. The method according to claim 7, further comprising: standardizing the inquiry item in the same manner that the item on the list was standardized to produce the bit array.
 9. The method according to claim 8, wherein the inquiry item comprises an address having a nine-digit zip code, a primary address number, and a secondary address number and standardizing comprises concatenating the nine-digit zip code, the primary address number, and the secondary address number.
 10. The method according to claim 7, wherein converting comprises computing a hash function for the inquiry item.
 11. The method according to claim 10, wherein the hash function is the secure hashing algorithm, SHA-1.
 12. The method according to claim 7, wherein determining bit positions comprises: extracting multiple n-bit samples from the N-bit object; and determining, for each n-bit sample, a bit position based on the n-bit sample.
 13. A computer for representing a list of items using a bit array wherein each bit in the bit array is initialized to a first value, the computer comprising: a memory having program instructions; and a processor, responsive to the programming instructions, configured to: convert each item to a N-bit object; determine bit positions based on the N-bit object; and set bits of the bit array to a second value at the determined bit positions.
 14. The computer according to claim 13, wherein the processor is further configured to: standardize each item of the list.
 15. The computer according to claim 14, wherein the list comprises addresses having a nine-digit zip code, a primary address number, and a secondary address number and standardizing comprises concatenating the nine-digit zip code, the primary address number, and the secondary address number.
 16. The computer according to claim 13, wherein converting comprises computing a hash function for each item.
 17. The computer according to claim 16, wherein the hash function is the secure hashing algorithm, SHA-1.
 18. The computer according to claim 13, wherein determining comprises: extracting multiple n-bit samples from the N-bit object; and determining, for each n-bit sample, a bit position based on the n-bit sample.
 19. A computer for determining whether an inquiry item is on a list of items, wherein the list is represented by a bit array having first and second values, the computer comprising: a memory having program instructions; and a processor, responsive to the programming instructions, configured to: convert the inquiry item to a N-bit object in a same manner that an item on a list was converted to produce a bit array; determine bit positions based on the N-bit object in a same manner that bit positions were determined for producing the bit array; and determine that the inquiry item is on the list if the bits of the bit array equal a second value at the determined bit positions and determining that the inquiry item is not on the list if at least one bit of the bit array does not equal a second value at the predetermined bit position.
 20. The computer according to claim 13, wherein the processor is further configured to: standardize the inquiry item in the same manner that the item on the list was standardized to produce the bit array.
 21. The computer according to claim 20, wherein the inquiry item comprises an address having a nine-digit zip code, a primary address number, and a secondary address number and standardizing comprises concatenating the nine-digit zip code, the primary address number, and the secondary address number.
 22. The computer according to claim 19, wherein converting comprises computing a hash function for the inquiry item.
 23. The computer according to claim 22, wherein the hash function is the secure hashing algorithm, SHA-1.
 24. The computer according to claim 19, wherein determining bit positions comprises: extracting multiple n-bit samples from the N-bit object; and determining, for each n-bit sample, a bit position based on the n-bit sample.
 25. A system for representing a list of items using a bit array wherein each bit in the bit array is initialized to a first value, comprising: means for converting each item to a N-bit object; means for determining bit positions based on the N-bit object; and means for setting bits of the bit array to a second value at the determined bit positions.
 26. The system according to claim 25, further comprising: means for standardizing each item of the list.
 27. The method according to claim 26, wherein the list comprises addresses having a nine-digit zip code, a primary address number, and a secondary address number and standardizing comprises concatenating the nine-digit zip code, the primary address number, and the secondary address number.
 28. The method according to claim 25, wherein converting comprises computing a hash function for each item.
 29. The method according to claim 28, wherein the hash function is the secure hashing algorithm, SHA-1.
 30. The method according to claim 25, wherein determining comprises: extracting multiple n-bit samples from the N-bit object; and determining, for each n-bit sample, a bit position based on the n-bit sample.
 31. A system for determining whether an inquiry item is on a list of items, wherein the list is represented by a bit array having first and second values, the system comprising: means for converting the inquiry item to a N-bit object in a same manner that an item on a list was converted to produce a bit array; means for determining bit positions based on the N-bit object in a same manner that bit positions were determined for producing the bit array; and means for determining that the inquiry item is on the list if the bits of the bit array equal a second value at the determined bit positions and determining that the inquiry item is not on the list if at least one bit of the bit array does not equal a second value at the predetermined bit position.
 32. The system according to claim 31, further comprising: means for standardizing the inquiry item in the same manner that the item on the list was standardized to produce the bit array.
 33. The system according to claim 32, wherein the inquiry item comprises an address having a nine-digit zip code, a primary address number, and a secondary address number and standardizing comprises concatenating the nine-digit zip code, the primary address number, and the secondary address number.
 34. The method according to claim 31, wherein converting comprises computing a hash function for the inquiry item.
 35. The method according to claim 34, wherein the hash function is the secure hashing algorithm, SHA-1.
 36. The method according to claim 31, wherein determining bit positions comprises: extracting multiple n-bit samples from the N-bit object; and determining, for each n-bit sample, a bit position based on the n-bit sample. 